Regenerative Rankine Cycle For Vehicles

ABSTRACT

A system for regenerating energy in a vehicle. The system includes a Rankine loop having a heat exchanger and a preheater configured to pre-heat a Rankine working fluid prior to the Rankine working fluid being heated at the heat exchanger. The system also includes an engine coolant loop configured to direct engine coolant to and from the pre-heater, and an exhaust loop configured to direct engine exhaust to and from the heat exchanger.

FIELD

The present disclosure relates to a regenerative Rankine cycle for vehicles.

BACKGROUND

This section provides background information related to the present disclosure, which is not necessarily prior art.

Rankine cycles have been included in vehicles, such as hybrid vehicles, to generate energy from waste heat of the vehicle. While such vehicle Rankine cycles are suitable for their intended use, they are subject to improvement. For example, it would be desirable to have a regenerative Rankine cycle that is more efficient, is able to reduce the load on components thereof and other vehicle components, and facilitates passenger cabin heating. The present teachings provide such an improved regenerative Rankine cycle.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

The present teachings provide for a system for regenerating energy in a vehicle. The system includes a Rankine loop having a heat exchanger and a preheater configured to pre-heat a Rankine working fluid prior to the Rankine working fluid being heated at the heat exchanger. The system also includes an engine coolant loop configured to direct engine coolant to and from the pre-heater, and an exhaust loop configured to direct engine exhaust to and from the heat exchanger.

The present teachings provide for an additional system for regenerating energy in a vehicle. The system includes an engine coolant loop, an exhaust loop, and a Rankine loop. The Rankine loop includes a preheater, a first heat exchanger, an expander, a generator, and a Rankine condenser. The first heat exchanger is configured to receive a Rankine fluid pre-heated by the preheater and hot exhaust from an engine of the vehicle. The first heat exchanger is configured to output hot Rankine working vapor. The expander is configured to receive the hot Rankine working vapor. The generator is configured to be driven by the expander and charge a battery. The Rankine condenser is configured to convert the hot Rankine working vapor back to the Rankine fluid.

The present teachings provide for a method for regenerating energy in a vehicle. The method includes the following: directing a Rankine fluid of a Rankine loop to a preheater to preheat the Rankine fluid; directing the preheated Rankine fluid and engine exhaust gas to a Rankine heat exchanger to further heat the pre-heated Rankine fluid using the engine exhaust gas to produce a hot Rankine working vapor; inputting the hot Rankine working vapor into an expander to cause the expander to drive a generator configured to charge a battery; and directing the hot Rankine working vapor to a Rankine condenser to convert the hot Rankine working vapor to the Rankine fluid.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of select embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 illustrates a vehicle including a system for regenerating energy according to the present teachings;

FIG. 2A is a diagram of a system for regenerating energy according to the present teachings;

FIG. 2B is a diagram of the system of FIG. 2A including multiple preheaters;

FIG. 3 is a diagram of another system for regenerating energy according to the present teachings; and

FIG. 4 is a diagram of yet another system for regenerating energy according to the present teachings.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

With initial reference to FIGS. 1 and 2A, a system 10 according to the present teachings for regenerating energy in an exemplary vehicle 12 is illustrated. Although the vehicle 12 is generally illustrated as a car, the system 10 can be used with any suitable vehicle, such as, but not limited to, the following: a truck; a van, a sports utility vehicle (SUV); a bus; a military vehicle; a train; a watercraft; any commercial vehicle; an aircraft; or any other suitable vehicle. In the example illustrated, the vehicle 12 generally includes an engine 14 for driving two or more wheels 16 of the vehicle 12. The engine 14 can be any suitable engine, such as an internal combustion engine. The vehicle 12 can be a hybrid or pure electric vehicle, and thus power for driving the wheels 16 may come from a battery 18 as well. The battery 18 may be used to drive the wheels 16 in conjunction with, or apart from, the engine 14 in any suitable manner.

The system 10 further includes a heating, ventilation, and air cooling (HVAC) unit 20 for conditioning air within a passenger cabin 22 of the vehicle 12. The HVAC unit 20 generally includes a heater core 24 for heating the passenger cabin 22, and an evaporator 26 for cooling the passenger cabin 22. Operation of the HVAC unit 20 will be described further herein in conjunction with other features of the system 10.

The system 10 further includes an engine coolant loop 30, an exhaust loop 40, an air cooling (AC) loop 50, and a Rankine loop 60. The engine coolant loop 30 generally includes the engine 14, a radiator 32, a preheater 34, a valve 36, and the heater core 24 of the HVAC unit 20. These features of the engine coolant loop 30 are in fluid communication with one another in any suitable manner, such as with a hose or any other suitable conduit configured to circulate a suitable engine coolant through the engine coolant loop 30. Any suitable engine coolant can be used.

During operation of the engine 14, the engine coolant absorbs heat from the engine 14 as the coolant passes through the engine 14. The engine coolant carries heat away from the engine 14 as the coolant flows from the engine 14 to the preheater 34. As described further herein, the preheater 34 can be any suitable heat exchanger configured to transfer heat from the hot engine coolant to a Rankine fluid of the Rankine loop 60.

From the preheater 34, the engine coolant flows to the valve 36, which routes the hot engine coolant either to the heater core 24 to heat the passenger cabin 22, or directly to the radiator 32 such that the hot engine coolant bypasses the heater core 24. The heater core 24 is any suitable heat exchanger suitable to exchange heat between the hot engine coolant and cold air of the passenger cabin 22 in order to heat the passenger cabin 22. From the heater core 24 the engine coolant is directed to the radiator 32. The radiator 32 facilitates release of heat from the engine coolant to the atmosphere in order to cool the engine coolant prior to the coolant being recirculated back to the engine 14, where the engine coolant again absorbs heat from the engine 14 in order to the cool the engine 14.

The exhaust loop 40 directs hot engine exhaust gas away from the engine 14 to a Rankine heat exchanger 62 of the Rankine loop 60. From the Rankine heat exchanger 62, the exhaust loop 40 directs the hot engine exhaust gas out of the vehicle, such as through a tailpipe. The hot engine exhaust gas is conveyed from the engine 14 to the Rankine heat exchanger 62 through any suitable conduit, such as any suitable pipe or hose.

The AC loop 50 will now be described. The AC loop 50 generally includes a compressor 52, an AC condenser 54, a thermal expansion valve (TXV) 56, and the evaporator 26. The AC loop 50 can further include a Rankine condenser 70 of the Rankine loop 60, as illustrated in FIGS. 2 and 4. However, the AC loop 50 need not include the Rankine loop 60, as illustrated in FIG. 3. These features of the AC loop 50 are connected in any suitable manner in order to circulate a suitable refrigerant through the AC loop 50, such as with any suitable hose or other conduit.

During operation of the AC loop 50, the refrigerant is in the form of a low pressure gas at about ambient temperature as it is pumped to the compressor 52. The compressor 52 compresses the gas refrigerant thereby increasing the pressure and temperature of the gas refrigerant. From the compressor 52, the refrigerant is pumped to the AC condenser 54, which condenses the gas into a liquid. As the liquid refrigerant is pumped through the TXV 56, the pressure and temperature of the refrigerant decreases to provide the refrigerant as a liquid with a relatively low pressure and low temperature. This low pressure and low temperature liquid refrigerant is pumped to the evaporator 26, where the refrigerant absorbs heat within the passenger cabin 22 in order to cool the passenger cabin 22. Heat of the passenger cabin 22 causes the refrigerant to change state from a liquid to a gas, and facilitates heat absorption. When the Rankine condenser 70 is included in the AC loop 50 as illustrated in FIGS. 2 and 4, the cooled gas refrigerant is pumped from the evaporator 26 to the Rankine condenser 70 in order to facilitate cooling of a Rankine working vapor as described further herein. From the Rankine condenser 70 the gas refrigerant returns to the compressor 52.

The Rankine loop 60 will now be described in detail. The Rankine loop 60 generally includes the preheater 34, the Rankine heat exchanger 62, an expander 64, the Rankine condenser 70, and a pump 72. These elements of the Rankine loop 60 are connected in any suitable manner, such as with any suitable conduit in order to direct a Rankine working fluid/vapor through the Rankine loop 60. The Rankine working fluid/vapor can be any suitable working fluid/vapor, such as water. The Rankine fluid is preheated by the preheater 34, which can be any suitable heater. For example, the preheater 34 can be a heat exchanger, such as a one-pass, two-pass, or a spiral heat exchanger. The preheater 34 can be included in both the Rankine loop 60 and the engine coolant loop 30 as illustrated in order to exchange heat therebetween. For example, the preheater 34 can advantageously facilitate transfer of heat from the engine coolant heated by the engine 14 to the Rankine working fluid in order to preheat the Rankine working fluid and reduce the temperature of the engine coolant.

The preheater 34 can be located at any suitable position throughout the Rankine loop 60. For example, the preheater 34 can be located before the Rankine condenser 70 along the direction of travel of the Rankine fluid so that the Rankine condenser 70 need not cool the Rankine working vapor as much. The Rankine loop 60 can also include multiple preheaters 34 positioned at any suitable location about the Rankine loop 60, as described below, for example. The preheaters 34 can be arranged in any suitable manner, such as in series or parallel.

From the preheater 34, the preheated Rankine working fluid is pumped to the Rankine heat exchanger 62, such as by the pump 72. At the Rankine heat exchanger 62, the preheated Rankine working fluid is further heated by the hot engine exhaust gas directed to the Rankine heat exchanger 62 from the engine 14. The Rankine heat exchanger 62 can be any suitable heat exchanger configured to facilitate transfer of heat from the hot engine exhaust gas released from the engine 14 to the preheated Rankine working fluid. The Rankine heat exchanger 62 is configured to raise the temperature of the preheated Rankine working fluid such that the Rankine working fluid changes state to a vapor.

The hot Rankine working vapor is directed from the Rankine heat exchanger 62 to the expander 64. The expander 64 can be a turbine, for example. The hot Rankine working vapor expands through the expander 64 and drives a crankshaft 66 of a motor or generator 68, which can recharge the battery 18. The motor/generator 68 can be any suitable device configured to recharge the battery 18.

From the expander 64, the hot Rankine working vapor is directed to the Rankine condenser 70. At the Rankine condenser 70, heat is released from the Rankine working vapor, and the Rankine working vapor is condensed back to a fluid. To facilitate cooling of the Rankine working vapor at the Rankine condenser 70, the refrigerant of the AC loop 50 can be directed through the Rankine condenser 70 as explained above. From the Rankine condenser 70, the Rankine working fluid passes through the pump 72 and back to the preheater 34. From the preheater 34, the Rankine working fluid can again be pumped to the Rankine heat exchanger 62 and through the Rankine loop 60.

The Rankine loop 60 can include multiple preheaters 34 positioned at any suitable location about the Rankine loop 60, such as in series or parallel. For example and with reference to FIG. 2B, the preheater 34 can be a first preheater, and a second preheater 34′ can be included in the Rankine loop 60. The second preheater 34′ can be any suitable heater, such as a cross-flow heat exchanger. In the example of FIG. 2B, the second preheater 34′ is located between the expander 64 and the Rankine condenser 70, and between the pump 72 and the first preheater 34. Thus, from the expander 64 the hot Rankine working vapor is directed through the second preheater 34′ to the Rankine condenser 70, where heat is released from the Rankine working vapor and the Rankine working vapor is condensed back to a fluid. From the Rankine condenser 70, the Rankine working fluid passes through the pump 72, again passes through the second preheater 34′, and then is directed back to the first preheater 34. As the Rankine working fluid passes through the second preheater 34′, it is heated by the hot Rankine working vapor simultaneously flowing through the second preheater 34′ from the expander 64. Thus, heat from the hot Rankine working vapor is transferred to the Rankine working fluid to heat the Rankine working fluid.

The second preheater 34′ provides numerous advantages. For example, this transfer of heat cools the hot Rankine working vapor prior to reaching the Rankine condenser 70, thereby reducing the load on the condenser 70 and increasing the efficiency of the condenser 70 to facilitate condensing of the hot Rankine working vapor to the Rankine working fluid. The transfer of heat to the Rankine working fluid also improves the efficiency of the Rankine loop 60 because the pre-heated working fluid input to the Rankine heat exchanger 62 will be at an even higher temperature, thereby facilitating the conversion of the Rankine working fluid to the Rankine working vapor at the Rankine heat exchanger 62.

With additional reference to FIG. 3, the system 10 for regenerating energy in the vehicle 12 can be modified to include an additional heat exchanger 80 configured to facilitate heating of the passenger cabin 22. The heat exchanger 80 can be located at any suitable position, such as within the HVAC unit 20, and can be any suitable heat exchanger, such as a positive temperature coefficient (PTC) heat exchanger. The Rankine loop 60 can be configured such that the hot Rankine working vapor is directed from the expander 64 to the heat exchanger 80 in order to supply additional heat to the passenger cabin 22. Specifically, heat from the hot Rankine working vapor is exchanged with cool air of the passenger cabin 22, thereby cooling the Rankine working vapor. The cooled (or less hot) Rankine working vapor is then directed to the Rankine condenser 70, where the Rankine working vapor is cooled further and converted back to the Rankine working fluid. Because heat from the Rankine working vapor is released to the passenger cabin 22 at the heat exchanger 80, the Rankine condenser 70 need not work as hard to reduce the temperature of the Rankine working vapor in order to condense the Rankine working vapor back into the Rankine working fluid. As illustrated in FIG. 3, the AC loop 50 need not circulate refrigerant through the Rankine condenser 70, and thus the AC loop 50 can be independent of the Rankine loop 60. Refrigerant from the AC loop 50 need not be circulated through the Rankine condenser 70 in part because the Rankine working vapor releases heat (thereby reducing the temperature of the Rankine working vapor) as the Rankine working vapor passes through the heat exchanger 80.

With reference to FIG. 4, the AC loop 50 can be configured to circulate the refrigerant through the Rankine condenser 70 in applications including the heat exchanger 80 through which the hot Rankine working vapor is circulated. The system 10 can take the configuration of FIG. 4 in applications in which the engine 14 generates a great amount of heat, for example when the vehicle 12 is a heavy duty vehicle, such as a truck. In such applications, the Rankine working vapor will be at an elevated temperature, thus requiring extensive cooling at the Rankine condenser 70. In order to alleviate the load on the Rankine condenser 70, heat from the Rankine working vapor is released at the heat exchanger 80 and the Rankine working vapor is cooled at the Rankine condenser 70 by refrigerant from the AC loop 50, which is circulated through the Rankine condenser 70.

The present teachings thus provide numerous advantages. For example, the system 10 is able to harness heat generated at the engine 14 in order to recharge the battery 18, as well as heat the passenger cabin 22. Furthermore, the preheater 34 enhances the efficiency and performance of the system 10, such as by, for example, reducing load on at least the heater core 24, the radiator 32, the Rankine heat exchanger 62, and the Rankine condenser 70. In particular, the preheater 34 reduces load on the radiator 32 by reducing the temperature of the engine coolant, the preheater 34 reduces the load on the Rankine heat exchanger 62 by heating the Rankine working fluid prior to being heated by the Rankine heat exchanger 62, the heat exchanger 80 reduces the load on the heater core 24 by providing additional heat to the passenger cabin 22, and the AC loop 50 reduces the load on the Rankine condenser 70 by reducing the temperature of the Rankine working vapor when the AC loop is connected to the Rankine condenser 70 as illustrated in FIGS. 2 and 4.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used in this application is for the purpose of describing particular example embodiments only and is not intended to be limiting. The singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). The term “and/or” includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The description has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. A system for regenerating energy in a vehicle comprising: a Rankine loop including a heat exchanger and a preheater configured to pre-heat a Rankine working fluid prior to the Rankine working fluid being heated at the heat exchanger; an engine coolant loop configured to direct engine coolant to and from the pre-heater; and an exhaust loop configured to direct engine exhaust to and from the heat exchanger.
 2. The system of claim 1, wherein the preheater is configured to transfer heat from the engine coolant loop to the exhaust loop.
 3. The system of claim 1, wherein the heat exchanger is configured to output engine exhaust gas and a heated Rankine working vapor.
 4. The system of claim 3, wherein the Rankine loop further comprises an expander configured to drive a generator, the generator configured to charge a battery.
 5. The system of claim 4, wherein the preheater is a first preheater, the system further comprising a second preheater between the expander and a condenser.
 6. The system of claim 3, wherein the Rankine loop further includes a Rankine condenser configured to cool and convert the heated Rankine working vapor into the Rankine working fluid.
 7. The system of claim 1, further comprising an air cooling loop including an evaporator, a compressor, an air cooling condenser, and a thermal expansion valve; wherein the air cooling loop is independent of the Rankine loop.
 8. The system of claim 1, further comprising an air cooling loop including an evaporator, a compressor, an air cooling condenser, and a thermal expansion valve; wherein the air cooling loop is in cooperation with the Rankine loop to cool the Rankine working vapor.
 9. The system of claim 3, wherein the heat exchanger is a first heat exchanger, and the system further comprises a second heat exchanger in receipt of the heated Rankine working vapor and configured to heat a passenger cabin of the vehicle.
 10. A system for regenerating energy in a vehicle comprising: an engine coolant loop; an exhaust loop; and a Rankine loop including: a preheater; a first heat exchanger configured to receive a Rankine fluid pre-heated by the preheater and hot exhaust from an engine of the vehicle, the first heat exchanger configured to output hot Rankine working vapor; an expander configured to receive the hot Rankine working vapor; a generator configured to be driven by the expander and charge a battery; and a Rankine condenser configured to convert the hot Rankine working vapor back to the Rankine fluid.
 11. The system of claim 10, further comprising a second heat exchanger in receipt of the hot Rankine working vapor and configured to heat a passenger cabin of the vehicle.
 12. The system of claim 10, further comprising an air cooling loop independent of the Rankine loop, the engine coolant loop, and the exhaust loop.
 13. The system of claim 10, further comprising an air cooling loop including an evaporator, a compressor, an air cooling condenser, and a thermal expansion valve; and wherein the air cooling loop is in cooperation with the Rankine loop to cool the hot Rankine working vapor.
 14. The system of claim 11, further comprising an HVAC unit including the second heat exchanger, a heater core, and an evaporator of an air cooling loop.
 15. A method for regenerating energy in a vehicle comprising: directing a Rankine fluid of a Rankine loop to a preheater to pre-heat the Rankine fluid; directing the preheated Rankine fluid and engine exhaust gas to a Rankine heat exchanger to further heat the preheated Rankine fluid using the engine exhaust gas to produce a hot Rankine working vapor; inputting the hot Rankine working vapor into an expander to cause the expander to drive a generator configured to charge a battery; and directing the hot Rankine working vapor to a Rankine condenser to convert the hot Rankine working vapor to the Rankine fluid.
 16. The method of claim 15, further comprising cooling the hot Rankine working vapor at the condenser with refrigerant of an air cooling loop.
 17. The method of claim 15, wherein the Rankine heat exchanger is a first heat exchanger, the method further comprising directing the hot Rankine working vapor to a second heat exchanger of an HVAC unit to heat a passenger cabin.
 18. The method of claim 15, further comprising pre-heating the Rankine fluid with a plurality of Rankine heat exchangers.
 19. The method of claim 15, further comprising directing hot engine coolant from the engine to the preheater to preheat the Rankine fluid.
 20. The method of claim 15, wherein the expander is a turbine. 